Building Instructions

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Use a medium-length wire to connect the motor to port A on the NXT.

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Use the shortest wire for this step.

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Connect the touch sensor's wire to port 1 on the NXT.

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This step builds the ammunition clip and loading pin.
Please see the Loading and Firing Instructions
to see how to use them. The pile of 3-hole beams are the bullets.
The ammunition clip will hold up to 10 bullets, although the magazine on
the gun will hold up to 15 bullets.

The ammunition clip and loading pin can be stored on
the gun as shown below. The gun will not fire with the clip in
place as shown. See the Loading and Firing
Instructions to learn how to load and fire the gun.

Machine Gun Programming

Use the program
Machine Gun for the Machine Gun. This program handles the
firing by spinning the motor as long as the trigger button (touch
sensor) is held down. The program also uses the orange button on
the NXT brick as a "safety" mode button, so that you can toggle the gun
in and out of safety mode, to keep it from going off by accident while
you are loading or carrying it.

Loading and Firing the
Machine Gun

The
machine gun must be carefully loaded to get the bullets into the proper
position and to prevent them from spilling out. See the
Loading and Firing Instructions.

Challenges

The
Machine Gun program uses
the touch sensor to trigger the firing of the gun. There are
several other ways you could imagine triggering the firing. For
example, take a look at some of the other
projects on this web site that use sensors... Does that
give you any ideas?

The
Machine Gun program makes
the machine gun "fully automatic", which means that it keeps firing
bullets as long as the trigger is held down. Can you modify
the program to make the gun "semi-automatic" (one bullet fired for
each press of the button), or add a semi-automatic mode?

The machine gun is
designed to be rapid-fire, but it is not very accurate. As an
advanced building challenge, you could try modifying the design to
make the contact between the bullets and the spinning arm more
consistent, or add something to force the bullets to shoot
straighter. Perhaps hitting the bullets sideways (on the flat
side) would help? You could also experiment with different
kinds of spinning arms or even different kinds of bullets.